The present invention relates to a device for producing an essentially T-shaped hollow profile or a hollow profile provided with at least one branch.
DE 199 09 928 C2 discloses a device for partly or completely severing a dome-like branch of a hollow body formed according to the internal high pressure forming process. The device has an encircling cutting edge, assigned to which is a supporting body which is arranged so as to be movable in such a way that it supports that region of the branch which is being deformed during the cutting operation, and the supporting body being inserted into a recess of the tool and surrounding the branch. A retaining ring adjoins the cutting edge. For the purpose of the internal high pressure forming of the hollow body, the device, the cutting ring and the retaining ring therefore form the requisite bearing surfaces. For the purpose of severing the dome-like branch, the retaining ring is axially displaced, so that the deforming region can radially expand and extend into the recess. The dome-like branch is therefore first shaped and then severed by the cutting edge released by the axially displaced retaining ring, it being possible for structural disturbances to occur in the parting region due to the severing.
DE 195 30 056 A1 discloses a method and a device for producing T-shaped hollow bodies having at least one dome-like branch. The method for producing a hollow body produced according to the internal high pressure forming process provides for a dome cap which is arranged at the end on the dome-like branch to be punched out, at an internal pressure increased relative to the maximum production internal pressure, by the counter holder which forms during the forming and supports the dome. For this purpose, a head-side end face of the counter holder is dimensioned to be larger than an active supporting surface and has a cutting edge bordering the active supporting surface in an encircling, collar-like manner. The counter holder, which normally serves to support the dome, is therefore also used at the same time for punching out the dome cap.
DE 195 30 055 A1 discloses a method and a device for producing double-walled apertures in components according to the internal high pressure forming process. In this case, a dome-like branch is imposed by the internal high pressure and the resulting dome cap is inverted inward by a first counter holder, supporting the dome developing during the forming, against a second counter holder supporting the component opposite the dome. The inversion is continued until the dome cap and that surface supported by the second counter holder form a double sheet layer, whereupon the dome cap is notched by the first counter holder, both counter holders are moved in the inversion direction, and sheet metal blanks are punched out of the double sheet layer. As a result, the forming of one or more dome-like branches, which is known per se in the case of internal high pressure forming, can be used for producing completely finished bosses in the hollow-body molded part.
DE 197 33 474 C2 discloses a method and a device for producing secondary molded elements on hollow profiles, the secondary molded elements being locally shaped by expansion of the hollow profile with a high fluid pressure generated in the latter and being in a closed form after completion of the production process, so that the secondary molded elements have to be opened by a further machining step.
DE 197 52 772 C2 discloses a method of producing an air-gap-insulated exhaust pipe provided with a branch piece. In this case, a connected profile is produced from two hollow profiles, which can be pushed one inside the other, by subsequent internal high pressure forming, this connected profile having a dome-like branch which is closed at the end of the production process. In order to open the branch produced, a dome cap at the end face is removed in a further step.
The present invention deals with the problem of specifying an improved embodiment for a device of the type mentioned at the beginning, this embodiment in particular allowing hollow profiles of high quality to be produced with at the same time high reproducibility.
In a device for producing an essentially T-shaped hollow profile, or a hollow profile provided with a branch, according to the internal high pressure forming process, the invention is based on the general idea of arranging in the region of the branch a tool which is designed as a cutting device and which is able to sever the branch by means of a parting slide displaceable essentially transversely to the axis of the branch. The device in this case has a multipart mold with which the hollow profile having at least one initially dome-like branch can be produced. Due to the design of the tool as a cutting device having a displaceable parting slide, an especially precise parting process can be achieved compared with the conventional opening of the branch.
The hitherto opening of the branches at the end face, which opening was achieved, for example, by tearing open the hollow profile under excess pressure at regions of cutting edges, may lead to an uneven hole pattern. At the same time, exact reproducibility and, associated therewith, a uniformly high quality are only possible to a limited extent with the known parting methods.
On the other hand, due to the solution according to the invention, the branch is cut off precisely by the parting slide and thus a component quality of the hollow profile considerably improved in the region of the parting location can be achieved. The cut quality can be additionally increased by a predeterminable drive speed of the parting slide and/or by an internal high pressure possibly applied during the parting. Furthermore, the cutting device ensures that a virtually uniform cut edge is obtained, so that the reproducibility can be markedly increased compared with conventional parting methods. At the same time, the invention enables the branch to be opened while still in the device directly after the forming operation, so that it is not necessary to remove the hollow profile from the device, and subsequent severing of the branch, for example by a laser or by a saw, is also not necessary, as a result of which the production process can be significantly rationalized.
According to an advantageous embodiment of the solution according to the invention, the parting slide is arranged inside a gap space which is present in the mold and through which a cavity passes transversely to the gap plane, this cavity being provided for shaping the branch. The arrangement of the parting slide inside the gap space ensures its exact fixing during the forming operation and guidance during the cutting operation without the need for a complicated mounting. This increases the robustness and the service life of the device according to the invention.
According to a further especially favorable embodiment, the parting slide has an opening which is orthogonal relative to the slide plane and through which the cavity provided for shaping the branch passes before the start of the parting operation, a marginal region of the opening forming a cutting edge. This offers the great advantage that the parting slide is arranged in the gap space during the parting operation in such a way that it projects at no point into the interior space which is defined by a shaping die impression of the device. The parting slide therefore in no way influences the process for forming the hollow profile or the process for shaping the dome-like branch. At the same time, the cutting edge at the marginal region of the opening ensures that the branch can be cut off directly after the forming process by displacement of the parting slide, thereby resulting in a very short production time overall.
The cutting edge may be designed to be interchangeable or as an integral part of the parting slide. An interchangeable cutting edge offers the advantage that, after a certain number of cutting operations, only the cutting edge has to be exchanged, whereas the rest of the parting slide, which is not impaired in its function by a worn cutting edge, can continue to be used. Especially in the case of hollow profiles of large diameters and thus in the case of parting slides of larger dimensions, this has a favorable effect on the ease of maintenance of the device, since only the cutting edge has to be exchanged and the possibly heavy parting slides can remain in the device. In contrast, in the case of hollow profiles or branches of small diameter, a parting slide having an integrated cutting edge is possibly more favorable, since it is simpler here to exchange the complete parting slide rather than laboriously carry out the exchange of the cutting edge.
According to a further favorable development of the solution according to the invention, the parting plane is arranged in a region between an end face region and a region at which the dome-like branch opens into the hollow profile. Due to the predefined arrangement of the parting plane, it is possible to sever the branch in each case at a desired plane and thereby determine a length of the branch by a corresponding arrangement of the parting plane. In this case, it is also conceivable for the parting plane to be arranged, in the limit case, at the end face region of the dome-like branch and for it to therefore cut off only an end-face dome cap without substantially shortening the length of the branch.
It goes without saying that the abovementioned features and the features still to be explained below can be used not only in the respectively specified combination but also in other combinations or on their own without departing from the scope of the present invention.
Preferred exemplary embodiments of the invention are shown in the drawings and are described in more detail below, the same designations designating identical or functionally identical or similar components.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings for example.